docs: cover tool content types, prompt image content, elicitation defaults, ping, legacy SSE serving (#2679)

examples/guides/clients/calling.examples.ts

@@ -201,5 +201,14 @@ const exported = await client.callTool(
 console.log(exported.content);
 //#endregion callTool_progress
 
+// "Check the connection" — the empty result the page quotes.
+//#region ping_basic
+const pong = await client.ping({ timeout: 5000 });
+console.log(pong);
+//#endregion ping_basic
+if (Object.keys(pong).length !== 0) {
+    throw new Error(`calling.md claim failed: ping resolved with ${JSON.stringify(pong)}`);
+}
+
 await client.close();
 await server.close();